1. Field of the Invention
The present invention relates to antibodies and their antigen-binding fragments and to other molecules that are capable of immunospecifically binding to B7-H1 or PD-1. In some embodiments such molecules are additionally capable of modulating the ability of B7-H1 or B7-DC to bind to PD-1 or are capable of affecting the signaling activity of the B7-H1 or PD-1. The invention additionally concerns the uses of such molecules in the diagnosis and the treatment of cancer and other diseases.
2. Description of Related Art
A. Cell Mediated Immune Responses
The immune system of humans and other mammals is responsible for providing protection against infection and disease. Such protection is provided both by a humoral immune response and by a cell-mediated immune response. The humoral response results in the production of antibodies and other biomolecules that are capable of recognizing and neutralizing foreign targets (antigens). In contrast, the cell-mediated immune response involves the activation of macrophages, natural killer cells (NK), and antigen-specific cytotoxic T-lymphocytes by T cells, and the release of various cytokines in response to the recognition of an antigen (Dong, C. et al. (2003) “Immune Regulation by Novel Costimulatory Molecules,” Immunolog. Res. 28(1):39-48).
The ability of T cells to optimally mediate an immune response against an antigen requires two distinct signaling interactions (Viglietta, V. et al. (2007) “Modulating Co-Stimulation,” Neurotherapeutics 4:666-675; Korman, A. J. et al. (2007) “Checkpoint Blockade in Cancer Immunotherapy,” Adv. Immunol. 90:297-339). First, antigen that has been arrayed on the surface of antigen-presenting cells (APC) must be presented to an antigen-specific naive CD4+ T cell. Such presentation delivers a signal via the T cell receptor (TCR) that directs the T cell to initiate an immune response that will be specific to the presented antigen. Second, a series of co-stimulatory and inhibitory signals, mediated through interactions between the APC and distinct T cell surface molecules, triggers first the activation and proliferation of the T cells and ultimately their inhibition. Thus, the first signal confers specificity to the immune response whereas the second signal serves to determine the nature, magnitude and duration of the response.
The immune system is tightly controlled by costimulatory and co-inhibitory ligands and receptors. These molecules provide the second signal for T cell activation and provide a balanced network of positive and negative signals to maximize immune responses against infection while limiting immunity to self (Wang, L. et al. (Mar. 7, 2011) “VISTA, A Novel Mouse Ig Superfamily Ligand That Negatively Regulates T Cell Responses,” J. Exp. Med. 10.1084/jem.20100619:1-16; Lepenies, B. et al. (2008) “The Role Of Negative Costimulators During Parasitic Infections,” Endocrine, Metabolic & Immune Disorders—Drug Targets 8:279-288). Of particular importance is binding between the B7.1 (CD80) and B7.2 (CD86) ligands of the Antigen Presenting Cell and the CD28 and CTLA-4 receptors of the CD4+ T-lymphocyte (Sharpe, A. H. et al. (2002) “The B7-CD28 Superfamily,” Nature Rev. Immunol. 2:116-126; Dong, C. et al. (2003) “Immune Regulation by Novel Costimulatory Molecules,” Immunolog. Res. 28(1):39-48; Lindley, P. S. et al. (2009) “The Clinical Utility Of Inhibiting CD28-Mediated Costimulation,” Immunol. Rev. 229:307-321). Binding of B7.1 or of B7.2 to CD28 stimulates T cell activation; binding of B7.1 or B7.2 to CTLA-4 inhibits such activation (Dong, C. et al. (2003) “Immune Regulation by Novel Costimulatory Molecules,” Immunolog. Res. 28(1):39-48; Lindley, P. S. et al. (2009) “The Clinical Utility Of Inhibiting CD28-Mediated Costimulation,” Immunol. Rev. 229:307-321; Greenwald, R. J. et al. (2005) “The B7 Family Revisited,” Ann. Rev. Immunol. 23:515-548). CD28 is constitutively expressed on the surface of T cells (Gross, J., et al. (1992) “Identification And Distribution Of The Costimulatory Receptor CD28 In The Mouse,” J. Immunol. 149:380-388), whereas CTLA4 expression is rapidly up-regulated following T-cell activation (Linsley, P. et al. (1996) “Intracellular Trafficking Of CTLA4 And Focal Localization Towards Sites Of TCR Engagement,” Immunity 4:535-543). Since CTLA4 is the higher affinity receptor (Sharpe, A. H. et al. (2002) “The B7-CD28 Superfamily,” Nature Rev. Immunol. 2:116-126), binding first initiates T cell proliferation (via CD28) and then inhibits it (via nascent expression of CTLA4), thereby dampening the effect when proliferation is no longer needed.
Further investigations into the ligands of the CD28 receptor have led to the identification and characterization of a set of related B7 molecules (the “B7 Superfamily”) (Coyle, A. J. et al. (2001) “The Expanding B7 Superfamily: Increasing Complexity In Costimulatory Signals Regulating T Cell Function,” Nature Immunol. 2(3):203-209; Sharpe, A. H. et al. (2002) “The B7-CD28 Superfamily,” Nature Rev. Immunol. 2:116-126; Greenwald, R. J. et al. (2005) “The B7 Family Revisited,” Ann. Rev. Immunol. 23:515-548; Collins, M. et al. (2005) “The B7 Family Of Immune-Regulatory Ligands,” Genome Biol. 6:223.1-223.7; Loke, P. et al. (2004) “Emerging Mechanisms Of Immune Regulation: The Extended B7 Family And Regulatory T Cells.” Arthritis Res. Ther. 6:208-214; Korman, A. J. et al. (2007) “Checkpoint Blockade in Cancer Immunotherapy,” Adv. Immunol. 90:297-339; Flies, D. B. et al. (2007) “The New B7s: Playing a Pivotal Role in Tumor Immunity,” J. Immunother. 30(3):251-260; Agarwal, A. et al. (2008) “The Role Of Positive Costimulatory Molecules In Transplantation And Tolerance,” Curr. Opin. Organ Transplant. 13:366-372; Lenschow, D. J. et al. (1996) “CD28/B7 System of T Cell Costimulation,” Ann. Rev. Immunol. 14:233-258; Wang, S. et al. (2004) “Co-Signaling Molecules Of The B7-CD28 Family In Positive And Negative Regulation Of T Lymphocyte Responses,” Microbes Infect. 6:759-766). There are currently several known members of the family: B7.1 (CD80), B7.2 (CD86), the inducible co-stimulator ligand (ICOS-L), the programmed death-1 ligand (PD-L1; B7-H1), the programmed death-2 ligand (PD-L2; B7-DC), B7-H3, B7-H4 and B7-H6 (Collins, M. et al. (2005) “The B7 Family Of Immune-Regulatory Ligands,” Genome Biol. 6:223.1-223.7; Flajnik, M. F. et al. (2012) “Evolution Of The B7 Family: Co-Evolution Of B7H6 And Nkp30, Identification Of A New B7 Family Member, B7H7, And Of B7's Historical Relationship With The MHC,” Immunogenetics epub doi.org/10.1007/s00251-012-0616-2).
B. B7-H1/PD1 Interactions
1. B7-H1
B7-H1 (PD-L1, CD274) is a particularly significant member of the B7 Superfamily as it is pivotally involved in shaping the immune response to tumors (Flies, D. B. et al. (2007) “The New B7s: Playing a Pivotal Role in Tumor Immunity,” J. Immunother. 30(3):251-260; U.S. Pat. Nos. 6,803,192; 7,794,710; United States Patent Application Publication Nos. 2005/0059051; 2009/0055944; 2009/0274666; 2009/0313687; PCT Publication No. WO 01/39722; WO 02/086083). B7-H1 is an approximately 33 kDa type 1 transmembrane protein. It has been speculated to play a major role in suppressing the immune system during particular events such as pregnancy, tissue allografts, autoimmune disease and other disease states such as hepatitis.
B7-H1 is broadly expressed in different human and mouse tissues, such as heart, placenta, muscle, fetal liver, spleen, lymph nodes, and thymus for both species as well as liver, lung, and kidney in mouse only (Martin-Orozco, N. et al. (2007) “Inhibitory Costimulation And Anti-Tumor Immunity,” Semin. Cancer Biol. 17(4):288-298). In humans, B7-H1 protein expression has been found in human endothelial cells (Chen, Y. et al. (2005) “Expression of B7-H1 in Inflammatory Renal Tubular Epithelial Cells,” Nephron. Exp. Nephrol. 102:e81-e92; de Haij, S. et al. (2005) “Renal Tubular Epithelial Cells Modulate T-Cell Responses Via ICOS-L And B7-H1” Kidney Int. 68:2091-2102; Mazanet, M. M. et al. (2002) “B7-H1 Is Expressed By Human Endothelial Cells And Suppresses T Cell Cytokine Synthesis,” J. Immunol. 169:3581-3588), myocardium (Brown, J. A. et al. (2003) “Blockade Of Programmed Death-1 Ligands On Dendritic Cells Enhances T Cell Activation And Cytokine Production,” J. Immunol. 170:1257-1266), syncyciotrophoblasts (Petroff, M. G. et al. (2002) “B7 Family Molecules: Novel Immunomodulators At The Maternal-Fetal Interface,” Placenta 23:S95-S101), resident macrophages of some tissues, or in macrophages that have been activated with interferon (IFN)-γ or tumor necrosis factor (TNF)-α (Latchman, Y. et al. (2001) “PD-L2 Is A Second Ligand For PD-1 And Inhibits T Cell Activation,” Nat. Immunol 2:261-268), and in tumors (Dong, H. (2003) “B7-H1 Pathway And Its Role In The Evasion Of Tumor Immunity,” J. Mol. Med. 81:281-287). In the mouse, B7-H1 protein expression is found in heart endothelium, islets cells of the pancreas, small intestines, and placenta (Martin-Orozco, N. et al. (2007) “Inhibitory Costimulation And Anti-Tumor Immunity,” Semin. Cancer Biol. 17(4):288-298).
2. PD-1
Programmed Death-1 (“PD-1”) is a receptor of B7-H1 and B7-DC. PD-1 is an approximately 31 kD type I membrane protein member of the extended CD28/CTLA4 family of T cell regulators (Ishida, Y. et al. (1992) “Induced Expression Of PD-1, A Novel Member Of The Immunoglobulin Gene Superfamily, Upon Programmed Cell Death,” EMBO J. 11:3887-3895; United States Patent Application Publication No. 2007/0202100; 2008/0311117; 2009/00110667; U.S. Pat. Nos. 6,808,710; 7,101,550; 7,488,802; 7,635,757; 7,722,868; PCT Publication No. WO 01/14557). Compared to CTLA4, PD-1 more broadly negatively regulates immune responses.
PD-1 is expressed on activated T cells, B cells, and monocytes (Agata, Y. et al. (1996) “Expression Of The PD-1 Antigen On The Surface Of Stimulated Mouse T And B Lymphocytes,” Int. Immunol. 8(5):765-772; Yamazaki, T. et al. (2002) “Expression Of Programmed Death 1 Ligands By Murine T Cells And APC,” J. Immunol. 169:5538-5545) and at low levels in natural killer (NK) T cells (Nishimura, H. et al. (2000) “Facilitation Of Beta Selection And Modification Of Positive Selection In The Thymus Of PD-1-Deficient Mice,” J. Exp. Med. 191:891-898; Martin-Orozco, N. et al. (2007) “Inhibitory Costimulation And Anti-Tumor Immunity,” Semin. Cancer Biol. 17(4):288-298).
The extracellular region of PD-1 consists of a single immunoglobulin (Ig)V domain with 23% identity to the equivalent domain in CTLA4 (Martin-Orozco, N. et al. (2007) “Inhibitory Costimulation And Anti-Tumor Immunity,” Semin. Cancer Biol. 17(4):288-298). The extracellular IgV domain is followed by a transmembrane region and an intracellular tail. The intracellular tail contains two phosphorylation sites located in an immunoreceptor tyrosine-based inhibitory motif and an immunoreceptor tyrosine-based switch motif, which suggests that PD-1 negatively regulates TCR signals (Ishida, Y. et al. (1992) “Induced Expression Of PD-1, A Novel Member Of The Immunoglobulin Gene Superfamily, Upon Programmed Cell Death,” EMBO J. 11:3887-3895; Blank, C. et al. (Epub 2006 Dec. 29) “Contribution Of The PD-L1/PD-1 Pathway To T-Cell Exhaustion: An Update On Implications For Chronic Infections And Tumor Evasion Cancer,” Immunol. Immunother. 56(5):739-745).
Antibodies capable of immunospecifically binding to murine PD-1 have been reported (see, e.g., Agata, T. et al. (1996) “Expression Of The PD-1 Antigen On The Surface Of Stimulated Mouse T And B Lymphocytes,” Int. Immunol. 8(5):765-772).
C. The Interactions of B7-H1 and PD-1
Interaction of B7-H1 and PD-1 has been found to provide a crucial negative co-stimulatory signal to T and B cells (Martin-Orozco, N. et al. (2007) “Inhibitory Costimulation And Anti-Tumor Immunity,” Semin. Cancer Biol. 17(4):288-298) and functions as a cell death inducer (Ishida, Y. et al. (1992) “Induced Expression Of PD-1, A Novel Member Of The Immunoglobulin Gene Superfamily, Upon Programmed Cell Death,” EMBO J. 11:3887-3895; Subudhi, S. K. et al. (2005) “The Balance Of Immune Responses: Costimulation Verse Coinhibition,” J. Molec. Med. 83:193-202).
Interaction between low concentrations of the PD-1 receptor and the B7-H1 ligand results in the transmission of an inhibitory signal that strongly inhibits the proliferation of antigen-specific CD8+ T cells; at higher concentrations the interactions with PD-1 do not inhibit T-cell proliferation but markedly reduce the production of multiple cytokines (Sharpe, A. H. et al. (2002) “The B7-CD28 Superfamily,” Nature Rev. Immunol. 2:116-126). T-cell proliferation and cytokine production by both resting and previously activated CD4 and CD8 T cells, and even naive T cells from umbilical-cord blood, have been found to be inhibited by soluble B7-H1-Fc fusion proteins (Freeman, G. J. et al. (2000) “Engagement Of The PD-1 Immunoinhibitory Receptor By A Novel B7 Family Member Leads To Negative Regulation Of Lymphocyte Activation,” J. Exp. Med. 192:1-9; Latchman, Y. et al. (2001) “PD-L2 Is A Second Ligand For PD-1 And Inhibits T Cell Activation,” Nature Immunol. 2:261-268; Carter, L. et al. (2002) “PD-1:PD-L inhibitory pathway affects both CD4(+) and CD8(+) T cells and is overcome by IL-2,” Eur. J. Immunol. 32(3):634-643; Sharpe, A. H. et al. (2002) “The B7-CD28 Superfamily,” Nature Rev. Immunol. 2:116-126).
B7-H1-PD-1 interactions lead to cell cycle arrest in G0-G1 but do not increase cell death (Latchman, Y. et al. (2001) “PD-L2 Is A Second Ligand For PD-1 And Inhibits T Cell Activation,” Nature Immunol. 2:261-268; Carter, L. et al. (2002) “PD-1:PD-L inhibitory pathway affects both CD4(+) and CD8(+) T cells and is overcome by IL-2,” Eur. J. Immunol. 32(3):634-643). Thus, B7-H1-PD-1 complexing has the ability to antagonize the B7-CD28 signal when antigenic stimulation is weak or limiting, and plays a key role in down-regulating T-cell responses.
The signal transduction mediated by B7-H1 and PD-1 is complex. Both molecules additionally bind to other proteins. B7-H1 is capable of binding to B7-1 (CD80) (Butte, M. J. et al. (2008) “Interaction of PD-L1 and B7-1,” Molecular Immunol. 45:3567-3572); PD-1 is capable of binding to B7-DC (PD-L2) (Lázár-Molnár, E. et al. (2008) “Crystal Structure Of The Complex Between Programmed Death-1 (PD-1) And Its Ligand PD-L2,” Proc. Natl. Acad. Sci. (USA) 105(30):10483-10488). B7-1 interacts with CD28 to deliver a co-stimulatory signal for T-cell activation that is important in the early stages of immune response (Elloso, M. M. et al. (1999) “Expression and Contribution of B7-1 (CD80) and B7-2 (CD86) in the Early Immune Response to Leishmania major Infection,” J. Immunol. 162:6708-6715). B7-DC is a strong stimulator of T cells, enhancing T cell proliferation and IFN-γ production. However, it also exhibits an inhibitory effect on the immune response via its interaction with PD-1 (Ishiwata, K. et al. (epub Jan. 10, 2010) “Costimulator Responses Induced by Nippostrongylus brasiliensis,” J. Immunol. 184:2086-2094). Microbes and tumors appear to have exploited PD-1 and B7-H1 to evade eradication by the immune system. Differences in binding affinities to the various receptors and ligands that interact with PD-1 and B7-H1 have been proposed to provide distinct functional outcomes of blockade of PD-1 and B7-H1 in disease models (Butte, M. J. et al. (2008) “Interaction of PD-L1 and B7-1,” Molecular Immunol. 45:3567-3572). The PD-1 pathway has also been implicated as playing a key role in the impairment of immune function during chronic infection (“T cell exhaustion”), and a blockade of PD-1 function is able to restore many T cell functions (Rodríquez-García, M. et al. (Nov. 19, 2010) “Expression Of PD-L1 And PD-L2 On Human Macrophages Is Up-Regulated By HIV-1 And Differentially Modulated By IL-10,” J. Leukocyte Biol. 89: doi:10.1189/jlb.0610327:1-9).
The role of B7-H1 and PD-1 in inhibiting T cell activation and proliferation has suggested that these biomolecules might serve as therapeutic targets for treatments of inflammation and cancer. The use of anti-PD1 antibodies to treat infections and tumors and up-modulate an adaptive immune response has been proposed (see, United States Patent Application Publication Nos. 2010/0040614; 2010/0028330; 2004/0241745; 2008/0311117; 2009/0217401; U.S. Pat. Nos. 7,521,051; 7,563,869; 7,595,048; PCT Publications Nos. WO 2004/056875; WO 2008/083174). Conversely, agents that modulate the interaction of PD-1 with B7-H1 have been suggested to have utility in up- or down-modulating the immune response (see, U.S. Pat. Nos. 7,029,674; 7,488,802; United States Patent Application Publications Nos. 2007/0122378; 2009/0076250; 2009/0110667; 2009/0263865; 2009/0297518; PCT Publication No. WO 2006/133396). Likewise, the use of anti-B7-H1 antibodies to treat infections and tumors and up-modulate an adaptive immune response has been proposed (United States Patent Application Publication Nos. 2009/0055944; 2009/0274666; 2009/0317368; U.S. Pat. Nos. 6,803,192; 7,794,710; PCT Publications Nos. WO 01/39722; WO 02/086083).
Nevertheless, despite all such advances a need remains for compositions capable of modulating the interaction between B7-H1 and PD-1. The present invention is directed to such compositions and their use to treat cancer and other diseases and conditions.